Tamper proof combination lock



Feb. 4, 1964 R. w. MAYNARD 3,120,11 7

TAMPER PROOFl COMBINATION LOCK --IIII INV ENT OR.

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Feb. 4, 1964 R. w. MAYNARD 3,120,117

TAMPER PROOF COMBINATION LOCK Original Filed April 27, 1960 2 Sheets--Sheeil 2 INVENTOR. W

HTTEA/Ey United States Patent O 3,120,117 TARIPER PROOF COMBINATION LGCK Robert W. Maynard, Cincinnati, hio, assigner to The Mosler Safe Co., Hamilton, Ohio, a corporation of New York Original application Apr. 27, 196B, Ser. No. 25,074. Di-

vided and this application Mar. 20, 1961, Ser. No.

2 Claims. (Cl. '7G-334) This invention relates to combination locks of the type employed on safes and vaults. It is specifically directed to a combination lock having improved means for protection against unauthorized opening.

This application is a division of my co-pending application Serial No. 25,074, filed April 27, 1960, entitled Tamper Proof Combination Lock.

Since the advent of the combination lock a number of methods have been developed by interested persons for surreptitiously opening locks without knowing the proper combinaton. One of the most effective of these techniques has proved to be the use of sound amplifying equipment to detect noises created as the dial of the lock is manipulated which may be used in a certain manner to indicate the position of the gates in the tumblers.

Combination locks of the type to which this invention is directed comprise a rotatable dial on the outside of the safe which is coupled through a driver connected to the dial shaft, to a set of circular tumblers in a lock case on the inside of the safe. Each tumbler is provided with a gate in its periphery and is so interconnected to the other tumblers by dogs and lost motion couplings that the gates of all the tumblers can be aligned at a given angular position only by a precise and unique set of left and right turns applied to the dial. When all the gates are aligned with respect to one another and are properly angularly oriented, a fence drops into the slot formed by the aligned gates, simultaneously establishing a drive connection between a notch in the driver and a dog integral with the fence. When the dial is further rotated in the proper direction, the dog draws in the bolt, to which it is connected by an angle bar, so that the lock may be opened. Locks of this general structure are conventional. This invention relates to improvements whereby locks of the character described are enabled to more effectively resist surreptitious attack by the various techniques which have been developed.

One of the objects of the present invention is the provision of a combination lock having means to create arbitrary and misleading sounds when the dial is turned, to defeat attempts to open the lock with sound detecting apparatus.

Further objectives and advantages of the invention can best be made apparent by reference to the following detailed description of the drawings in which a preferred embodiment of the invention is disclosed.

In the drawings,

FIGURE 1 is a top view, partly in section, of a combination lock in accordance with this invention mounted on a safe door, showing the arrangement of the respective elements in the lock case;

FIGURE 2 is a view of the case with the cover plate removed, showing the bolt in the extended or locked position;

FIGURE 3 is a view of the cover plate subassembly showing the tumblers mounted thereon;

FIGURE 4 is a partial sectional view taken on line 4-4 of FIGURE 2, showing the driver and sounder disc assembly; and

FIGURE 5 is a View of the sounder disc, taken on line 5 5 of FIGURE 4.

In FIGURE 1, a combination lock incorporating the ICS principles of this invention is shown mounted on a safe door denoted generally by 1. A dial 2 for setting the combination and operating the lock is located on the outside 3 of the door. The dial is rotatably connected through the safe door by an arbor 4 to the lock assembly proper, which is denoted generally at 5 and is mounted on the inside 6 of the door.

The dial 2 is journalled in a fixed frame 7 provided with an index mark S. A series of numbers is embossed around the circumferenece of the dial in the usual manner.

Both the dial and its frame are generally conventional. While the dial shown is numbered from zero to one hundred, it will be appreciated that this is for purposes of illustration only and that combinations of any series of numbers might equally Well be used.

This invention particularly relates to the lock assembly 5 mounted on the inside of the door. This assembly is enclosed within a generally rectangular housing comprising a hollow case 9 and a cover plate 10. Certain of the lock elements are mounted from the case while other cooperating elements are mounted on the cover plate, as will be more fully described.

The case 9 is mounted on the safe door 1 by machine screws 11 accessible only from the interior of the case. The cover plate 10 is secured to the case by machine screws (not shown) which pass through openings 12 in the cover plate and are threaded into the case at 13.

The drive shaft or arbor 4 is positively connected to the dial and is journalled in the frame 7, extending through an opening 14 in the safe door and into the interior of the case. The arbor is externally threaded as at 15 and is provided with a pair of diametrically opposite longitudinal keyways 16 at the end which extends into the case.

A driver, which is indicated generally at 17 (FIGURES 1, 2 and 4), is threaded on the arbor in the interior of the case and its bore is equipped With keyways 19 which match the keyways 16.

The driver comprises a hollow cylindrical shaft 18 and a shoulder 20 of large diameter. The face of the shoulder which is toward the bottom or rear wall 21 of the case is provided with a step numbered 23, of smaller diameter. The step 23 carries a sounder disc 24. T he circumference of the shoulder 2t) is confgurated with a notch 23, the shape of which can best be seen from FIGURE 2. The portions 2 of the circumference of shoulder 20 on either side of notch 28 constitute inwardly sloping cam surfaces, as will be explained. A drive dog 3) extends outwardly from the forward face of shoulder 20 near its periphery.

The driver 17 is positively keyed to the arbor 4, onto which it is threaded for axial adjustment, by means of the two-pronged key 32 as shown in FIGURE 4. When the dial is turned and the arbor rotated, the driver is thus positively rotated with it.

The sounder disc 24 mounted on step 23 of the driver shoulder is a circular metal member, preferably made of brass, slotted or notched on its periphery as at 33. Interiorly, the disc 24 is provided with a right-angular ange which is loosley tted on step 23 and which extends into a groove 34 on the driver shoulder. The lock case 9 is provided wtih a raised boss 35 of dimension smaller than the notch 33, so located that when sounder disc is mounted on the driver, boss 35 sits inside of notch 33. The sounder disc is thereby prevented from freely rotating with the driver but is capable of rotating through a limited range between the points which the sides of notch 33 abut the boss.

By reason of the limited movement permitted sounder disc 24, it causes a confusing click or noise when the dial is jiggled or oscillated.

The bolt 37 of the lock shown for purposes of illustration is a generally rectangular bar which is longitudinally movable in slots 38 and 4t) respectively presented by two corner blocks 41 and 42 formed integrally with the case. When the bolt is in the position shown in AFIGURE 2 in which it extends outwardly through an opening in the case wall, its outer end engages a cooperating slot in the safe frame, not shown, whereby the safe door is locked. Withdrawal of the bolt inside the case permits Y the door to be opened. The bolt is freely slidable in slots 38 and 40 so that it may readily be drawn in when the proper combination has been set. i

Movement of the bolt in slots 38 and 40 is governed by angle bar generally designated by 54, which connects the inner end of the bolt to the driver 17 once the proper combination has been set, so that an angular rotation of the driver is transformed into a linear movement of the bolt. The angle bar is best pictured in FGURES l and Y2. At one end, the angle bar is provided with a clevis 59, to straddle the bolt. to the bolt by a stud 55.

Shank 56 of the angle bar 54 extends diagonally from the bolt to the upper'part of the case, above the driver. At its other end, the angle bar has a downwardly extending dog 57 for engagement in the notch 28 with the driver. A fence 58 extends laterally from the angle bar adjacentV the dog and is so arranged that when the dog 57 engages notch 28, the fence engages the aligned gates. A tension spring 6i) is connected from a post 61 presented by the case to a point 62 on the shank 56 of the yangle bar-so that the bar is constantly urged downwardly (counterclockwise in FIGURE 2), whereby dog 57 is urged toward the periphery of shoulder 20. Y

Rotatably journalled on the cover plate are the lock tumblers, four in the embodiment shown, numbered 78, 79, 8i) and 81. More or fewer may be used as desired.

The clevis is pivotally connected The tumblers themselves may be of known type,- for example of the type described in my previously referredY to application Serial No. 25,074, and need not be described in detail herein.

The lock is opened by rotating dial 2 to the left and right in accordance with the combination to which the lock has been set. Since thisgoperation is conventional and well understood, it need not be described here in detail. During the setting of the combination, until all the gates are aligned, dog S7 rides upon the periphery of the driver, fence 58 being spaced a slight distance outwardly of the tumblers so that the tumbler gates cannot be located by feel as the fence moves past them. When the driver hasl been rotated to a position corresponding to that in FIGURE 2, the dog gradually moves off cam surface 29 and attempts to drop into notch 28; if the gates are unaligned, then the fence is slowly lowered onto the circumference of one or all the tumblers, and remains thereon until dog 57 is gently raised by the cam surface 29 on the other side of the notch.

Once' the gates have been aligned, dog 57 is permitted to engage notch 28, the fence simultaneously moving into the gates. As the driver is now rotated counter- 4 clockwise dog 57 is driven to the left, the angle bar pulling stud with it, and the bolt is permitted to slide in slots 3S and 40.

The sounder disc 24 generates false clicks or sounds inside the case which are, or misleadingly might be, similar to the sound made by the dog 57 as it touches' cam surfaces 29, or the sound made by any gate edge engaging the fence as it passes by. Y

The manner in which the sounder disc operates is as follows: As the dial is turned, the sounder disc tends to turn with the driver 17. However, the extent of its rotation is limited by the points at which the boss 35 contacts the sides of the notch 33 into which the boss extends. Thus, the sounder disc may be rotated a short distance at most before one or the other sides of the notch hits the boss, which creates a small but audible metallic click. This sound indicates nothing at all with respect to the position of the tumblers or driver, and therefore confuses anyone who, for example, is attempting to detect with sound equipment the sound of dog 57 striking the driver cam surfaces 29, and thereby determine the dial positions at which the combination is set. v

While I have described a preferred embodiment of this invention, the invention is not limited to that embodiment alone but also includes other modifications and variations within the scope of the following claims.

Having described my invention, I claim:

l. In a combination lock having a rotatable arbor, a sound-creating device comprising a member which is loosely coupled to said arbor and which if unimpeded rotates with said arbor as the latter ,is rotated, said member having a squared notch presenting a pair of opposed abutment edges, and means for arresting the rotation of said member, said means presenting a pair of opposed relatively fixed abutment walls for engaging the respec- `tive abutment edges of said notch when said arbor is rotated, noise thereby being created at changing angular positions of said arbor upon each rotation thereof in alternate directions.

2. In a combination lock having a rotatable arbor, a sound-creating device comprising a member which is loosely coupled to said arbor and which if unimpeded References Cited in the file of this patent UNITED STATES PATENTS 326,424 Gassen sept. 15, 1885 1,017,871 Himioben Feb. 12, 1912 1,655,840 Nichin Jan. 10, 192s 

1. IN A COMBINATION LOCK HAVING A ROTATABLE ARBOR, A SOUND-CREATING DEVICE COMPRISING A MEMBER WHICH IS LOOSELY COUPLED TO SAID ARBOR AND WHICH IF UNIMPEDED ROTATES WITH SAID ARBOR AS THE LATTER IS ROTATED, SAID MEMBER HAVING A SQUARED NOTCH PRESENTING A PAIR OF OPPOSED ABUTMENT EDGES, AND MEANS FOR ARRESTING THE ROTATION OF SAID MEMBER, SAID MEANS PRESENTING A PAIR OF OPPOSED RELATIVELY FIXED ABUTMENT WALLS FOR ENGAGING THE RESPECTIVE ABUTMENT EDGES OF SAID NOTCH WHEN SAID ARBOR IS ROTATED, NOISE THEREBY BEING CREATED AT CHANGING ANGULAR POSITIONS OF SAID ARBOR UPON EACH ROTATION THEREOF IN ALTERNATE DIRECTIONS. 